*
    margin:0;
    padding:0;

body
    display flex 
    flex-direction column//主轴设置为垂直方向
    justify-content center
    align-items center
    height 100vh //相对单位
    overflow hidden //隐藏滚动条
  

 .container
     display flex
     width 90vw
    .panel
     height 80vh
     border-radius 50px
     color #fff
     cursor pointer
     flex 0.5
     margin 10px
     position relative
     background-size cover
     background-position center
     background-repeat no-repeat
     transition all 0.7s ease-in// 过渡效果
    h3
       font-size 24px
       position absolute
       left 20px
       bottom 20px
       margin 0
       opacity 0
       transition opacity 300ms ease-in 400ms
    &.active
        // background green
        flex 5
        h3 
            opacity 1
@media (max-width: 480px) {
  .container {
    width: 100vw;
  }
   .panel:nth-of-type(4),
   .panel:nth-of-type(5){
    display:none; 
}
}
